1. Field of the Invention
The present invention relates to a surface property measuring device comprising a detector having, a stylus for measuring surface property, typically, surface roughness, and a driving mechanism for causing the detector to advance and retreat along a surface to be measured, more particularly to a surface property measuring device which is superior in straightness and reproducibility exhibited when the detector advances and retreats, and which is low in cost.,
Further, the present invention relates to a surface property measuring device comprising a detector having a stylus arm provided with the stylus in the vicinity of a leading end thereof, and more particularly to a surface property measuring device comprising a detector which is capable of measuring micro surface property by a low measuring force.
2. Description of the Prior Art
There has been widely used a surface roughness measuring device of applying a stylus on a surface to be measured, and measuring the surface roughness by detecting a surface roughness-direction-wise displacement of the stylus while advancing and retreating a detector including the stylus along the surface to be measured, to thereby convert the detected displacement into an electrical signal and then process the electrical signal in a predetermined manner.
There have been proposed various driving mechanisms for causing the detector to advance and retreat along the surface to be measured.
For example, there is, as shown in FIG. 22, described in Japanese Patent Publication (Kokoku) No. 4-60523 a surface roughness measuring device comprising a sliding shaft 34 held on a bearing 33, which is disposed on a frame 32 of the driving mechanism, and sliding in an advancing and retreating, direction (in the direction shown by the arrow A) of a detector 10, a driving-side connector 40 attached to the sliding shaft 34 through a moving block 36 and a leaf spring 38, a feed block 44 fixed to the sliding shaft 34 through a connecting portion 42 for causing the sliding shaft 34 to advance and retreat in the direction shown by the arrow A, a feed screw 46 engaged with the feed block 44, a reduction gear 50 connected to the feed screw 46 through a coupling 48, and a motor 52 for rotation-driving the reduction gear 50.
In FIG. 22, reference numeral 14 designates a detector-side connector pin attached to a rear end (on the right-hand end of the drawing) of a case 12 of the detector 10 and engaged with the driving-side connector 40, 18 a stylus arm having a stylus 16, which moves up and down while following the surface to be measured, at a leading end thereof (on the left-hand end of the drawing) and swinging in the case 12 with a fulcrum (20) as a center, 20 a leaf spring shaped like a substantially L, constituting the fulcrum of the stylus arm 18, 22 an inductance type displacement detector disposed in the vicinity of a rear end of the stylus arm 18 for detecting an up-and-down movement of the rear end of the stylus lever 18, 24 a skid for absorbing minute irregularities in the vicinity of the stylus 16 to thereby obtain a stable measured value, and 26 a nose for protecting the stylus 16 and the stylus arm 18.
This Japanese Patent Publication (Kokoku) No. 4-60523 aims to propose a compact stationary surface roughness measuring device. However, it has a construction in which the sliding shaft 34 itself advances and retreats in the frame 32 of the driving mechanism 30 in the direction shown by the arrow A, thereby disabling the sliding shaft 34 to be elongated so much, which causes the moving stroke of the detector 10 to be placed under restriction. Furthermore, the sliding shaft 34 as a moving part is connected to the detector 10 through the moving block 36, the leaf spring 38, the connector 40, and so on, thereby making the bearing 33 susceptible to the external force, which provides problems of making it difficult to maintain a stable and highly accurate straightness, and so on.
On the other hand, the applicant proposes in, Japanese Provisional Patent Publication (Kokai) Nos. 61-155901 and 61-155701 a stylus type measuring device in which, as its main part is shown in FIG. 23, a guide shaft 54 is fixed to a frame of a driving mechanism (not shown) in parallel with an advancing and retreating direction of a detector, 10 (in a lateral direction of the drawing), and the detector 10 is attached to a feed nut 45 which slides on the guide shaft 54 and is moved by a feed screw 46 rotated by a motor 52.
In. FIG. 23, reference numeral 16 is a stylus, 56 a slide rod fixed to the feed nut 45, 58 a vertical guiding member vertically connected to a leading end of the slide rod 56, 60 is a sliding member attached to the vertical guiding member 58 slidably up and down, 62 a holding member to hold the detector 10 rotatably attached to the sliding member 60, 64 a switch pin fixed to the feed nut 45, and 66, 68 are a fore end and a rear end limit switch which turn on at an advancing limit position (hereinafter referred to as xe2x80x9cthe fore endxe2x80x9d) or an retreating limit position (hereinafter referred to as xe2x80x9cthe rear endxe2x80x9d).
However, also the stylus type measuring device, proposed in Japanese Provisional Patent Publication (Kokai) Nos. 61-155901 and 61-155701 cannot sufficiently secure a span of the feed nut 45 to the guide shaft 54; therefore, not only the feed nut 45 is easily susceptible to the external force, but also it undergoes a large saccadic movement due to the dimension error of the component, which does not makes it easy to maintain a stable and highly accurate straightness.
Besides, the applicant proposes in Japanese Utility Model Publication (Kokoku) No. 4-24408 a surface roughness measuring device in which, as its main part is shown in FIG. 24, a guide ""shaft 54, is fixed to a frame 32 of a driving mechanism 30 in parallel with an advancing and retreating direction of the detector 10 (in a lateral direction of the drawing), and the detector 10 is attached to one of a pair of movable pieces 70, 72 (the movable piece 70 in the drawing) which are moved by a feed screw 46 rotated by a motor 52.
In FIG. 24, reference numeral 74 designates a pair of tension springs for urging both the movable pieces 70, 72 in the direction nearer to each other to thereby eliminate the backlash.
However, also the surface roughness measuring device proposed in Japanese Utility Model Publication (Kokoku) No. 4-24408 has the same problems as Japanese Provisional Patent Publication (Kokai) Nos. 61-155901 and 61-155701.
On the other hand, there is described in Japanese Provisional National Publication (Kohyo) No. 8-503311 that a slide rod, to which a detector is attached, is positioned by being pressed obliquely on to an L-like slide surface in a driving mechanism by a leaf spring, a driving belt is engaged between pulleys disposed in the vicinities of a fore and a rear end of the driving mechanism, respectively, the slide rod is fixed to a part of the belt, and the rotation of the pulleys causes a detector, attached to a leading end of the slide rod, to retreat. The device proposed therein has a large saccadic movement due to the dimension error of the component, which makes it difficult to maintain. a stable and highly accurate straightness.
Furthermore, according to any one of the prior arts, the wire to the detector 10 in the driving mechanism 30 is made of a lead wire; therefore, according to the kind of the wire or the wiring manner of the wire, a part of the wire easily undergoes excessive bending, an unstable load, or the like is applied to a connector with the detector and a driving mechanism such as a sliding member, which provides a bad influence to the straightness and the reproducibility.
Besides, there are proposed, as a mechanism for supporting a stylus arm 18 in the detector 10 and providing a measuring force thereto, not only a mechanism provided with one leaf spring 20 having both of a function as a fulcrum and a function of providing a measuring force, as shown in Japanese Patent Publication (Kokoku) No. 4-60523, but also a mechanism in which, as proposed in Japanese Patent Publication (Kokoku) No. 3-30084 and Japanese Provisional Patent Publication (Kokai) No. 6-258003, a coil spring 86 is, as shown in FIG. 25, disposed in a tension manner between a location slightly apart from a bearing portion 82 of an arm holder 80 holding a stylus arm 18 and a measuring force-adjusting screw 84 attached to a case 12 (Japanese Patent Publication (Kokoku) No. 3-30084), or a slider adjusted in location by a screw rod (Japanese Provisional Patent Publication (Kokai) No. 6-258003), one end of the coil spring 86 is adjusted in location in the direction shown by the arrow B by the measuring force adjusting screw 84 or the slider, which provides a measuring force while absorbing the backlash of the bearing portion 82.
The applicant proposes in Japanese Provisional Utility Model Publication (Kokai) No. 1-104504 that two coil springs 92, 94 provide, as shown in FIG. 26, a minute measuring force to a stylus arm 18 supported by a cross-like spring 90.
However, the mechanism using a bearing, proposed in Japanese Patent Publication (Kokoku) No. 3-30084 and the mechanism using two coil springs, proposed in Japanese Provisional Utility Model Publication (Kokai) No. 1-104504, have many components, which provides a problem that the assembling and the adjustment are difficult. In particular, the mechanism which eliminates the backlash of the fulcrum and adjusts the measuring force by one coil spring, proposed in Japanese Patent Publication (Kokoku) No. 3-30084, makes it difficult to set the optimum points of the both.
On the other hand, as proposed in Japanese Patent Publication (Kokoku) No. 4-60523 and Japanese Provisional Utility Model Publication. (Kokai) No. 1-104504, when the fulcrum is formed by the leaf spring, the fulcrum is fixed by the leaf spring, thereby preventing the fulcrum shaft from shifting, which provides a stable accuracy. However, as proposed in Japanese Patent Publication (Kokoku) No. 4-60523, when the leaf spring is independently used, there is a problem that the change of the thickness or the bending of the leaf causes the measuring force to be changed, which makes the adjustment difficult.
Furthermore, a special detector such as a deep-slot-use prove detector having a long stylus has a problem that the change of the weight of the stylus arm causes the measuring force to change.
The present invention has been made in order to solve the above-mentioned conventional problems. It is therefore a first object of the present invention to make the sliding member not to be affected by the external force, and then reduce the saccadic movement of the sliding member due to the dimension error, thereby stably being affected by a straightness with high accuracy at a low cost.
It is a second-object of the invention to prevent the detector, the connector, and the sliding section from receiving an unstable load, and then prevent the straightness and the reproducibility from being affected by a bad influence.
It is a third object of the invention to make the measuring force accurately adjustable by means of a simple construction.
The invention of claim 1 provides a surface property measuring device comprising a detector having a stylus, and a driving mechanism for causing the detector to advance and retreat along a surface to be measured, wherein the device comprising a columnar guide fixed to a frame of the driving mechanism in parallel with an advancing and retreating direction of the detector, a sliding member sliding on the columnar guide, elongated in the advancing and retreating direction of the detector, and engaged with the columnar guide at least two of a fore and a rear location thereof, and driving means for causing the sliding member to advance and retreat along the columnar guide, and wherein the detector is attached to the sliding member, which results in solution of the above-mentioned first object.
According to the invention of claim 1, the columnar guide can be elongated, and portions of the sliding member for receiving the sliding portion can be arranged with its span wide, which makes the sliding member not to be affected by the external force, and then reduces the saccadic movement of the sliding member due to the dimension error, thereby stably providing a straightness with high accuracy at a low cost. This results in improvement of the reproducibility and stabilization of the accuracy, and then reduces the number of the components and facilitates the assembling, with low cost.
In the invention, the columnar guide is provided in plural, and one of the columnar guides is inserted through the sliding member, whereas the others of the columnar guides is adapted to press the sliding member, so as to obtain more stability.
In the invention, the sliding member is rectangular and is elongated in the advancing and retreating direction of the detector, and the one of the columnar guides is inserted through two of the fore and the rear location.
In the invention of claim 2, the detector is detachable to the driving mechanism through connectors, wherein a driving-side connector is fixed to the sliding member.
In the invention of claim 3, at least a portion of a cable, which connects the driving mechanism with the detector, to be deformed due to a movement of the detector comprises a flexible printed circuit board, which results in solution of the above-mentioned second object.
The invention of claim 4 provides a surface property measuring device comprising a stylus arm having a stylus at the vicinity of a leading end thereof, wherein a fulcrum of the stylus arm is made of a thin plate, and the stylus arm is applied with a force directed in such a direction as to cause the stylus to contact to a surface to be measured, by means of a coil spring which is independent of the thin plate, which results in solution of the above-mentioned third object.
According to the invention of claim 5, no bearing is used, thereby reducing the number of the components and making the assembling and the adjustment easy, with low cost. Also, the fulcrum is fixed using the thin plate, thereby preventing the fulcrum shaft from shifting, with stabilized accuracy. Further, when the leaf spring is independently used, the thickness change and the bend of the leaf causes the measuring force to be changed, thereby making the adjustment difficult; however, the invention of claim 4 is capable of setting the measuring force in designing, and easily adjusting the measuring force. Moreover, when eliminating the saccadic movement of the fulcrum and simultaneously adjusting the measuring force are carried out by only one leaf spring, the thickness change and the bend of the leaf, and the like provide a large fluctuation, thereby making it difficult to set the optimum points of both of eliminating the saccadic movement and adjusting the measuring force. However, according to the invention of claim 4, no saccadic movement initially occurs on the fulcrum, the coil spring has only to be adjusted taking account of the optimum measuring force only, which makes it easy to adjust the measuring force.
In a special detector such as a deep-slot-use detector having a long stylus, if the weight of the stylus arm is changed, the dispersion of the measuring force among the products can be lowered by changing the thickness and the shape of the leaf spring and simultaneously adjusting the urging force of the coil spring.
In the invention of claims 5 and 6, the thin plate is more different (weaker) in elastic force in the vicinity of the fulcrum than at the other portions, so as to reduce fluctuations in position of the fulcrum.
In the invention of claim 7, the thin plate is shaped like a cross and fixed to a frame of the detector at both end portions thereof, and a stylus arm is fixed to a center portion of the thin plate, so as to prevent fluctuations in position of the fulcrum.
In the invention of claim 10, an urging force of the coil spring is adjustable.
In the invention of claims 8 and 9, the thin plate comprises a leaf spring, and the leaf spring provides a reaction force which is opposed to an urging force by the coil spring, and the balance between the reaction force and the urging force by the coil spring provides a measuring force to the stylus, which provides a minute measuring force with high accuracy.
These and other novel features and advantages of the present invention are described in or will become, apparent from the following detailed description of preferred embodiments.